as someone who has used Alpine Trekkers, or tour wreckers as I often call them, and a true AT set up.....I say go with the AT set up forsure.
This, though, does depend on the type of touring you are doing. If you are touring maybe 5 days a year or less you may as well go with trekkers as they will save you a lot of money and they do work ok.
I had issues with my trekkers. Mine eventually broke, were replaced by BCA, and I sold them and got Fritschi Freeriders.
Much much nicer, IMO. Trekkers worked well, but are really clanky and hold you really high off the ski. THey were just not extremely user friendly.
Freeriders was a vast vast improvment. Much nicer going up, and they work great coming down.
If you are touring for more than a couple of hours than the weight difference between the two gets to be noticable. So, if you're spending all day going up and down you really get to notice the difference.
Skiing wise, they aren't race stocks......There is some lateral flex associated with them, but nothing horrible. And this only really affect you on groomed condition, in Pow they work great.
Recently some guys did a stiffness test on both AT and some alpine bindings. Freeriders and the newest Naxo did much better than the marker bindings that were tested, with about 50% less flex.
If you know how to actually land cliffs and don't ski like a fuck up freeriders are fine in most situation. I've hucked about 15 feet on mine before and haven't broken them, and I've seen friends huck 30 footer before and have no problems.
They do break more easily than regular bindings, but they aren't as unreliable as was stated above. Most people I know are extremely pleased with them
So, if you want to actually get seriously in to touring, which I totally recommend as Pow in the backcountry never stops =), get a set of freeriders or the New Naxos. They are worth the extra money.
if you are just going to be doing small hour long skins outside of ski areas and such a few times a year, Trekkers should be fine. You'll save a lot of money and get to use your alpine bindings.
So, figure out which type of tourer you want to be and decide from there
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